An architecture of decentralized control for multi-degrees of freedom parallel manipulator

Decentralized control is composed of more than two subsystems. Subsystems communicate each other to control the whole system. In this paper, information of mechanical constraint for a parallel manipulator is analyzed. When some joints of multi-degrees of freedom parallel manipulators are set to be passive, excessive interference force can be reduced. A case where one joint of 3-linked arms is set to be passive is treated. The influence of a passive joint to the tip of the arm is derived by the configuration and the calculated reference torque. In the active joints, the interference force information from other joints are used to compensate the effect of passive joint. Such information is also used for switching passive joints. As a result, the avoidance of singular point is realized. Taking advantage of a parallel manipulator which has redundant drive joints, fault compensation is achieved by extending the communication of subsystems. Comparison with centralized control represents the availability of the decentralized control system by simulation.